The man accused of killing a coworker in her Hillsborough home admitted he strangled her to death, according to an affidavit filed with the Somerset Court court.

Juan Jimenez-Olivera, 29, of Hillsborough told police he strangled 30-year-old Sviatlana Dranko and then started a blaze at her home by lighting a bedsheet and the couch on fire, Detective Edward Conway said in the affidavit. Dranko is identified in the affidavit only as a "Jane Doe," but a statement from law enforcement Friday disclosed her identity.

Jimenez-Olivera provided details of the crime that were consistent with Dranko's injuries and evidence at the scene of her burnt home, Conway said in the affidavit.

The affidavit doesn't specify a motive, and authorities did not disclose one in a statement sent to media Friday. CBS New York reports Jimenez-Olivera and Dranko worked together at a pizzeria.

Jimenez-Olivera was arrested Thursday in relation to the death and fire at Dranko's Bloomingdale Drive residence, according to a statement by Somerset County Prosecutor Geoffrey D. Soriano, Somerset County Prosecutor's Office Chief of County Detectives Timothy Fitzgerald and Hillsborough Township Chief of Police Paul Kaminsky.

At about 8:23 a.m. Tuesday, Hillsborough Police, along with several Hillsborough Township Fire Departments, responded to a 911 call for a residential fire in a Bloomingdale Drive apartment and townhouse complex, the statement said.

Fire personnel entering the residence found Dranko deceased on the second floor of the dwelling, and further investigation found that she was already dead prior to the setting of the fire, the statement said.

CONNECT WITH US

Arson investigators found that the fire, which had been deemed suspicious, was intentionally set within two separate origin points, the statement said.

Jimenez-Olivera was identified as being responsible for Dranko's death and the setting of the fires after detectives followed numerous leads, conducted many interviews, and processed crime scene evidence, and was placed under arrest at the Somerset County Prosecutor's Office, the statement said.

The statement didn't specify how Dranko was killed or what evidence specifically tied Jimenez-Olivera to her death, and the affidavit only says the "subsequent investigation" led authorities to him. Prosecutor's office spokesman Capt. Jack Bennett said Jimenez-Olivera came to the prosecutor's office voluntarily. An earlier version of this story, published before Bennett responded to an inquiry from NJ.com, said authorities didn't specify how Jimenez-Olivera came to be at the office.

Jimenez-Olivera was charged with first-degree homicide and second-degree aggravated arson, the statement said.

He was lodged at the Somerset County Jail in lieu of $1 million cash-only bail set by Judge Julie M. Marino in Somerville. His first appearance was Friday afternoon.

Detectives from the Hillsborough Township Police, the Somerset County Prosecutor's Office Major Crimes Unit, the Somerset County Prosecutor's Office Crime Scene and Forensics Unit, the Somerset County Prosecutor's Office Arson Task Force and the New Jersey Regional Medical Examiner's Office all took part in the investigation, the statement said.

The investigation and arrest was a collaborative effort by detectives from the Hillsborough Township Police Department and the Somerset County Prosecutor's Office, with assistance from the New Jersey State Police and various regional FBI offices throughout the United States, according to the statement.

The statement didn't explain why FBI offices from out of the area were involved.

"The detectives involved in this investigation worked tirelessly to promply apprehend the individual responsible for this very tragic case," Soriano said. "The law enforcement community is extremely grateful to all who assisted in this investigation and its collective heart goes out to Ms. Dranko's family."

Soriano, Fitzgerald and Kaminsky request anyone with information regarding this investigation contact the Hillsborough Police at 908-369-4323, the Somerset County Prosecutor's Office Major Crimes Unit at 908-231-7100, the Somerset County Crime Stoppers' Tip Line at 888-577-TIPS (8477). The Somerset County Crime Stoppers' Tip Line can also be reached by filling out this form online. All tips are kept confidential.